Cable operators have widely deployed high-speed data services on cable television systems. These data services allow subscriber-side devices, such as personal computers, to communicate over a cable network. A Modular Cable Modem Termination System (M-CMTS) connects the cable network to a data network, such as the Internet. A downstream Edge Quadrature Amplitude Modulation (EQAM) located in the cable network receives data transferred from the M-CMTS over a packet switched portion of the network (which can be characterized as having variable transmission delays), performs modulation and other processing, and then transfers the modulated data over a Hybrid Fiber Coaxial (HFC) portion of the cable network, which is specified as a constant transmission delay portion.
Because the variable EQAM receive data rate can sometimes exceed a rate that some or all of the EQAM components are processing packets, multiple components of the EQAM are equipped with relatively large buffers to queue up data to be output. Equipping each of these components with relatively large buffers prevents the further reduction in cost to manufacture the EQAM. Also, processing the buffered data can produce delays that can be sufficient to disrupt operation of the cable modems. The disclosure that follows solves this and other problems.